This invention relates to a method of texturizing a proteinaceous substance, particularly a mycelial fungal mass.
Mycelial fungi produced under controlled conditions can be suitable for use as a foodstuff for humans and may be desirably texturized so as to resemble the appearance of natural meat to make it more acceptable as a foodstuff. Texturizing techniques are disclosed in co-pending British Patent Applications Nos. 25385/75 and 25387/75.
A portion of British Patent Application No. 25385/75 now British Pat. No. 1,508,635 reads as follows:
"According to the present invention there is provided a method of texturizing a mycelial fungal mass having reduced turgor and a solids content of between 20% and 35% by weight, which includes passing the mass under pressure through at least one apertured member whereby the mass is filamented and compacting said filaments to form a textured structure. Preferably the mass is passed in succession through a plurality of meshes each having a different mesh size.
The invention also includes apparatus for texturizing a mycelial fungal mass having reduced turgor and a solids content of between 20% and 35% by weight, which includes means for feeding the mass to a die, at least one mesh size within the range of 0.3 to 2.0 mm within the die through which the mass is passed to effect filamenting of the mass and compacting means for reducing the cross-sectional size of the filamented mass to produce a textured structure.
Conveniently, the feeding means may include a screw-type positive displacement pump located within a housing attached to a die and operated at ambient temperature. The die may incorporate two mesh structures, the first mesh structure being of a fine nature and the second mesh structure being of a more coarse nature and a compacting head, having an internal taper, attached near to the outlet from the second mesh structure."
A portion of British Patent Application No. 25387/75 now British Pat. No. 1,502,455 reads as follows:
"According to the present invention there is provided a method of texturizing a mycelial fungal mass having reduced turgor and a solids content of between 20% and 40% by weight, which includes rolling the mass between two relatively moving surfaces to elongate the mass into a cylinder in which groups of hyphae are attenuated and entangled to a substantial extent to give a textured structure.
The invention also includes a method of texturizing a mycelial fungal mass having reduced turgor and a solids content of between 20% and 40% by weight, which includes rolling of the mass between two relatively moving surfaces to form an elongate cylinder, juxtaposing at least two sections of the cylinder to form a tiered mass, repeat rolling the tiered mass to form a further elongate cylinder, juxtaposing at least two sections of the further cylinder and successively repeating the procedure finishing with a rolling step to give a textured structure.
The invention also includes apparatus for texturizing a mycelial fungal mass having reduced turgor and a solids content of between 20% and 40% by weight, which includes a stationary base and a movable endless belt spaced therefrom defining two relatively movable surfaces, said surfaces converging in the direction of movement such that the said mass is moved in when placed in contact with both said surfaces so as to form an elongate cylinder of said mass, and means located at the downstream end of said surfaces for manipulating said cylinder to form a tiered mass for further elongation into a textured structure."
If texturized in accordance with Application No. 25385/75, the mass will have a solids content of beteen 20% and 35% by weight and if texturized in accordance with Application No. 25387/75 the mass will have a solids content of between 20% and 40% by weight. In either case, the average solids content will be approximately 30% by weight and the average water content will be approximately 70% by weight. The free water in the mass may range from 30% by 57% and the bound water from 3% to 25% depending on the condition of the mycelial fungi. On average, the free water will be approximately 54% by weight and the bound water approximately 16% by weight.
In this Specification, "free water" is defined as the percent of the total wet sample which is freezable as measured by differential scanning calorimetry and "bound water" is defined as the difference between the total water and the free water.
U.S. Pat. No. 4,056,638 issued to Huang et al discloses a process for heating and drying a fungal material comprising treating the same by rapid dielectric heating to reduce the moisture content from 8 to 40 weight percent to give a produce with a solids level of 30 to 70 weight percent. The patent discloses that dielectric heating puffs and heat sets the material which can then be further dried at a much slower rate by conventional means such as hot air. The resulting product can be rehydrated to absorb from 1 to 5 times its weight of water. The patent stresses the difference between its dielectric heating step and conventional drying means.
U.S. Pat. No. 4,001,459 issued to Kim et al discloses a method of preparing a texturized protein material comprising freezing an aqueous mixture of a heat coagulable protein by cooling the mixture in a manner and at a rate effective to produce elongated ice crystals generally aligned perpendicular to the surface of cooling, freeze-drying the frozen mass, and heat-setting the resulting dried protein material. The list of usable protein materials given in the patent includes single-cell protein. The heat-setting can be done by the use of moist heat.
It is an object of the present invention to progress further in the texturization process of the mycelial fungal mass starting from a texturization technique disclosed as the above-mentioned British Patent Applications, although it should be appreciated that other initial texturization techniques may be employed.